Hi everyone,
Besides my heating question, I also have concerns about the insulation of the floor slab.
Attached is the construction plan created by the energy consultant. As you can see, he recommends 5cm (2 inches) of insulation below the floor slab. However, since our house (a bungalow) is built on strip foundations all around, I’m not really sure how sensible this is.
According to the architect, the floor slab should simply rest on the strip foundations on the compacted soil. If the insulation is placed below the floor slab but the strip foundations themselves are not insulated, I don’t understand the purpose, since they are also made of concrete and this seems to negate the effect of the insulation. The construction manager also mentioned that the buildup inside the house is too high (8cm (3 inches) of insulation plus underfloor heating), and suggested I should rather put 10cm (4 inches) of insulation under the floor slab.
Wouldn’t it be cheaper and more sensible to instead put the total 13cm (5 + 8) of insulation on top of the floor slab? Or would this create a thermal bridge since the masonry walls (36.5cm (14 inches) Ytong or Bisotherm blocks) rest directly on the floor slab?
Maybe someone here has experience with strip foundations and can reassure me or share their solution.
Thanks in advance.
Besides my heating question, I also have concerns about the insulation of the floor slab.
Attached is the construction plan created by the energy consultant. As you can see, he recommends 5cm (2 inches) of insulation below the floor slab. However, since our house (a bungalow) is built on strip foundations all around, I’m not really sure how sensible this is.
According to the architect, the floor slab should simply rest on the strip foundations on the compacted soil. If the insulation is placed below the floor slab but the strip foundations themselves are not insulated, I don’t understand the purpose, since they are also made of concrete and this seems to negate the effect of the insulation. The construction manager also mentioned that the buildup inside the house is too high (8cm (3 inches) of insulation plus underfloor heating), and suggested I should rather put 10cm (4 inches) of insulation under the floor slab.
Wouldn’t it be cheaper and more sensible to instead put the total 13cm (5 + 8) of insulation on top of the floor slab? Or would this create a thermal bridge since the masonry walls (36.5cm (14 inches) Ytong or Bisotherm blocks) rest directly on the floor slab?
Maybe someone here has experience with strip foundations and can reassure me or share their solution.
Thanks in advance.
S
Sebastian7920 Mar 2016 08:09Sand, 5cm (2 inches) lean concrete base layer, 25cm (10 inches) ground slab, welded membrane, 7cm (3 inches) PUR insulation board, thermal conductivity 0.023 W/(m·K)
S
Sebastian7920 Mar 2016 08:50Insulation for an uninsulated ground slab – walls are very good heat conductors.
The benefits are debated in relation to the costs – especially since this is more commonly used with poorly insulating bricks like calcium silicate.
The benefits are debated in relation to the costs – especially since this is more commonly used with poorly insulating bricks like calcium silicate.
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